The present invention relates to an orthodontic appliance, more particularly orthodontic arch wires and orthodontic brackets, having a special coating or plating thereon.
As is well known in the art, orthodontic appliances, such as orthodontic metal arch wires and orthodontic brackets, can be made of stainless steel. More recently, however, improved arch wires have been made of so-called "shape memory" alloys. Before heat setting, the alloy can be bent and shaped, resulting in permanent conformation changes. If the alloy is reshaped after heat setting, it seeks to return to its original conformation. These properties are utilized in orthodontic arch wires in that, in the patient's mouth, the wire seeks to the return to its original conformation, thereby providing the necessary forces to patient's teeth.
Orthodontic arch wires made of such "shape memory" alloys are also known as superelastic or semi-superelastic arches. Examples of such arches include those made of a nickel-titanium alloy such as Nitinol sold by Unitek Corporation.
As noted in U.S. Pat. No. 5,399,087 and 5,538,422 to Arndt, it has not been possible to weld metal to arches made of "shape memory" alloys. Thus, it is not possible to weld or solder an auxiliary part, such as a post, hook or loop, to such arch wires. Rather, it has been necessary to use crimp tube adapters or, as disclosed in the Arndt patent, a sheath insert in order to secure auxiliary parts to "shape memory" arches.
Therefore, it is desirable to provide an orthodontic metal arch wire, including an arch wire made of a "shape memory" alloy, to which an auxiliary part can be or is soldered.
It is also desired to provide an orthodontic appliance, e.g., an orthodontic metal arch wire or bracket, whether made of stainless steel or a shape memory alloy, which has a bright, smooth and easy to clean surface, thereby improving aesthetics, reducing corrosion, and reducing the coefficient of friction of the wire surface.